In telecommunications networks, routes are defined for conveying data packets between different items of routing equipment, referred to herein for simplicity as “routers”.
All routers have a plurality of communication interfaces with the network. Each router uses a communications protocol, and some are arranged to generate a plurality of different communication protocols for conveying data packets.
In conventional manner, a given router thus has a unitary database of routing information for each routing protocol and referred to as its “routing information base” (RIB). For example, a given router can have therein a routing information base for routing protocols for use between domains and known as exterior gateway protocols (RIB-EGP), and another routing information base for routing protocols for use within a domain and known as “interior gateway protocols” (RIB-IGP).
These unit databases are combined by the router to form an operational routing plan referred to as a “forwarding information base” (FIB) corresponding to all of the unitary databases taken together and including special management of route superpositions, so as to obtain a data structure giving all routing solutions for a given router.
This operational routing plan is then transmitted to all of the interfaces of the router to enable them to route packets in independent and coherent manner.
In such a telecommunications network, when a malfunction occurs, e.g. the result of a given router being unavailable, all or some of the other routers in the network need to modify their operational routing plans in order to adapt to the degraded mode of operation of the network.
In existing methods for managing malfunctions, fault detection is followed by a period of propagating information devoted to warning all of the routers whose operation will be disturbed by the fault.
Each router then recalculates new routing paths and updates the unitary database relating to the associated protocol. This update is followed by recalculating the operational routing plan, which then needs to be transferred to each of the interfaces.
These operations are lengthy and complex, and they are made worse by having large numbers of interfaces and routes.
In particular, the time required for calculating the updates for each unitary database and then for calculating the operational routing plan, followed by the time required for transferring the plan to all of the interfaces, leads to the router being unavailable in a manner that is particularly detrimental for the network as a whole.